JP2008286074A - Control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent vibrating operation of a throttle valve when target throttle opening is calculated based on a target torque in relation to a control device for an internal combustion engine. <P>SOLUTION: This control device for the internal combustion engine is provided with a target torque set-up means setting up target torque, a target throttle opening calculation means calculating target throttle opening for materializing the target torque according to the target torque and engine rotation speed based on a characteristic model of an engine intake system, an engine rotation speed detection means detecting an actual engine rotation speed, and a discrete rotation speed calculation means calculating discrete rotation speed making the actual engine rotation speed a discrete value with a predetermined step width. The discrete rotation speed is used as an engine rotation speed input in the target throttle opening calculation means. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a control device for an internal combustion engine.

  Japanese Patent Application Laid-Open No. 10-18887 discloses a technique that uses a front-rear differential pressure of a throttle valve and a target air amount when obtaining a target throttle opening for obtaining a target torque. Japanese Patent Laid-Open No. 2006-70701 discloses a technique that uses an intake system model that takes into account the engine speed when obtaining the target throttle opening.

Japanese Patent Laid-Open No. 10-18887 JP 2006-70701 A

  The actual engine speed in the vehicle may fluctuate finely in a short cycle due to the influence of various inputs such as fluctuations in auxiliary drive driving load, torsional vibration of the transmission or drive shaft, or fluctuations in running resistance. When the engine speed is included in the process for calculating the target throttle opening as in the conventional technique described above, if the engine speed fluctuates in a short period, the target throttle opening also decreases in a short period. Will fluctuate. For this reason, when the throttle valve is driven and controlled based on the target throttle opening, the throttle valve repeats vibrational operation, and a load is imposed on the throttle valve.

  The present invention has been made in order to solve the above-described problems, and in the case of calculating the target throttle opening based on the target torque, an internal combustion engine capable of preventing the vibration operation of the throttle valve can be prevented. An object is to provide a control device.

In order to achieve the above object, a first invention is a control device for an internal combustion engine,
Target torque setting means for setting the target torque of the internal combustion engine;
A target throttle opening calculating means for calculating a target throttle opening for realizing the target torque according to the target torque and the engine speed, based on a characteristic model of the engine intake system;
Engine speed detecting means for detecting the actual engine speed;
Discretized rotational speed calculation means for calculating a discrete rotational speed obtained by discretizing the actual engine rotational speed with a predetermined step width;
With
The discretized rotational speed is used as the engine rotational speed input to the target throttle opening degree calculation means.

The second invention is the first invention, wherein
The actual engine speed is NE, the step width is K, and N is
K × (N-1) <NE <K × N
Is a natural number that satisfies
The discretized rotational speed calculation means calculates the discretized rotational speed as K × N when the internal combustion engine is accelerated, and calculates the discretized rotational speed as K × (N−1) when the internal combustion engine is decelerated. It is characterized by that.

The third invention is the first or second invention, wherein
Acceleration / deceleration calculating means for calculating acceleration and / or deceleration of the internal combustion engine;
Step width changing means for changing the step width based on the acceleration and / or deceleration;
It is characterized by providing.

Moreover, 4th invention is set in 3rd invention,
The step width changing means increases the step width when the acceleration and / or the deceleration is larger than a predetermined value as compared with the case where the acceleration and / or the deceleration is not larger than the predetermined value.

  According to the first invention, when the target throttle opening for realizing the target torque is calculated according to the target torque and the engine speed based on the characteristic model of the engine intake system, the actual engine speed is It is possible to calculate a discretized rotational speed that has been discretized with a predetermined step width, and to calculate the target throttle opening using the discretized rotational speed. The discretization rotational speed does not vary with a short cycle of fluctuations in the actual engine rotational speed. For this reason, if the target throttle opening is calculated using this discretized rotational speed, it is possible to reliably prevent the target throttle opening from fluctuating in a short cycle. Therefore, it is possible to reliably prevent the throttle valve from repeating the vibration operation, and to avoid a burden on the throttle valve.

  According to the second invention, the discretization rotational speed is higher than the actual engine rotational speed when the internal combustion engine is accelerated, and is lower than the actual engine rotational speed when the internal combustion engine is decelerated. That is, at the time of acceleration or deceleration, the discretized rotational speed corresponds to the engine rotational speed slightly ahead of the actual engine rotational speed (future). For this reason, according to the second aspect of the invention, the target throttle opening is calculated by prefetching the engine speed during acceleration or deceleration. Therefore, it is possible to respond more quickly to a torque request for acceleration or deceleration, and it is possible to improve acceleration and deceleration responsiveness.

  According to the third aspect of the invention, the step width of the discretized rotational speed can be changed based on the acceleration or deceleration of the internal combustion engine. For this reason, a more appropriate step width can be set according to the magnitude of acceleration and deceleration of the internal combustion engine.

  According to the fourth aspect of the invention, when the acceleration or deceleration of the internal combustion engine is greater than a predetermined value, the step width of the discretized rotational speed can be increased compared to the case where it is not. When the acceleration or deceleration of the internal combustion engine is large, the change in the actual engine speed is fast. Therefore, it is preferable to increase the step width because the sudden operation of the throttle valve can be prevented more reliably. On the other hand, when the acceleration or deceleration of the internal combustion engine is small (including the steady state), it is preferable to reduce the step width because the deviation between the actual engine speed and the discretized speed becomes smaller. According to the fourth invention, in view of the above, a more appropriate step width can be set according to the magnitude of the acceleration and deceleration of the internal combustion engine.

Embodiment 1 FIG.
[Description of system configuration]
FIG. 1 is a diagram for explaining a configuration of an internal combustion engine system according to Embodiment 1 of the present invention. The system shown in FIG. 1 includes an internal combustion engine 10 mounted on a vehicle. The number of cylinders and the cylinder arrangement of the internal combustion engine 10 are not particularly limited. A piston 12 is provided in each cylinder of the internal combustion engine 10. An intake passage 16 and an exhaust passage 18 communicate with each cylinder.

  An electronically controlled throttle valve 20 is provided in the intake passage 16. A throttle position sensor 22 that detects the opening of the throttle valve 20 (hereinafter referred to as “throttle opening”) is provided in the vicinity of the throttle valve 20. A catalyst 26 for purifying the exhaust gas is disposed in the exhaust passage 18.

  Each cylinder of the internal combustion engine 10 is further provided with a fuel injector 28 for injecting fuel into the intake port, an ignition plug 30 for igniting an air-fuel mixture in the combustion chamber, an intake valve 32, and an exhaust valve 36. ing. The present invention is not limited to the port injection type engine as shown in the figure, but can be applied to an in-cylinder direct injection type engine or an engine using both port injection and in-cylinder direct injection.

  A crank angle sensor 42 for detecting the rotation angle (crank angle) of the crankshaft 24 is provided in the vicinity of the crankshaft 24 of the internal combustion engine 10. An accelerator position sensor 44 for detecting the accelerator opening is installed in the vicinity of the accelerator pedal.

  Further, the system includes an engine ECU (Electronic Control Unit) 50. An engine ECU (hereinafter simply referred to as “ECU”) 50 includes various sensors such as the throttle position sensor 22, the crank angle sensor 42, and the accelerator position sensor 44 described above, the throttle valve 20, the fuel injector 28, and the spark plug 30 described above. Etc. are electrically connected to each other.

  The system further includes an ABS-ECU 52 that controls the antilock brake system of the vehicle, and a VSC-ECU 54 that controls the vehicle stability control system (Vehicle Stability Control).

[Features of Embodiment 1]
In the present embodiment, a plurality of required torques are output to the internal combustion engine 10. As this required torque, for example, the required torque calculated by the driver based on the accelerator opening, the auxiliary equipment drive required torque required to drive the auxiliary equipment, the ABS output from the ABS-ECU 52 Requested torque, VSC required torque output from VSC-ECU 54, and the like.

  The ECU 50 calculates the target torque by collecting and arbitrating the plurality of required torques. Further, the ECU 50 calculates a target throttle opening for realizing the target torque, and controls the operation of the throttle valve 20 based on the target throttle opening.

  FIG. 2 is a functional block diagram when the ECU 50 calculates the target throttle opening. The ECU 50 first converts the target torque into the target intake air amount by the torque-air amount conversion means 56. Next, the target throttle opening is calculated by compensating the target intake air amount by the air response delay compensating means 58. The air response delay compensation means 58 is an inverse model of a model that takes into account the response delay of the throttle valve 20, the response delay of the intake valve 32, and the response delay due to the volume of the intake passage 16 (an inverse model of the intake system model and an inverse model of the throttle model). ).

  Such a method for calculating the target throttle opening is described in, for example, Japanese Patent Application Laid-Open No. 2006-70701, and is well known, so that further explanation is omitted here.

  By the way, the relationship between the target torque and the target air amount varies depending on the engine speed. For this reason, the engine speed is input to the calculation by the torque-air amount conversion means 56. Further, the response delay of the air actually sucked into the cylinder also varies depending on the engine speed. Therefore, the engine speed is also input to the calculation by the air response delay compensation means 58.

  The actual engine speed in the vehicle may fluctuate finely in a short cycle due to the influence of various inputs such as fluctuations in auxiliary drive driving load, torsional vibration of the transmission or drive shaft, or fluctuations in running resistance. For this reason, when the target throttle opening is calculated, if the engine speed detected by the crank angle sensor 42 is directly input to the torque-air amount conversion means 56 or the air response delay compensation means 58, the engine speed is calculated. Due to the fluctuation, the target throttle opening is also likely to fluctuate in a short cycle. When the target throttle opening fluctuates in a short cycle, the throttle valve 20 repeats the vibration operation, and a load is applied to the throttle valve 20.

  In order to avoid the inconveniences as described above, in the present embodiment, a discrete rotation in which the engine speed detected by the crank angle sensor 42 (hereinafter referred to as “actual engine speed” and represented by the symbol NE) is converted into a discrete value. The number f (NE) is calculated, and the discretized rotational speed f (NE) is input to the torque-air amount conversion means 56 and the air response delay compensation means 58. In the present embodiment, the discretized rotation speed f (NE) is expressed by the following equation.

In the above equation (1), K is a step width. N is the following formula
K × (N-1) <NE <K × N (2)
It is a natural number that satisfies

  FIG. 3 is a diagram showing the relationship between the actual engine speed NE and the discretized speed f (NE) when the step width K is 40 rpm. As shown in this figure, the discretized rotational speed f (NE) calculated by the above equation (1) does not vary along with a short cycle fluctuation in the actual engine rotational speed NE. Therefore, if the discretized rotational speed f (NE) is input to the torque-air amount conversion means 56 or the air response delay compensation means 58 to calculate the target throttle opening, the target throttle opening fluctuates in a short cycle. This can be surely prevented. Therefore, it is possible to reliably prevent the throttle valve 20 from repeating the vibration operation, and to avoid a burden on the throttle valve 20.

  As shown in FIG. 3, the discretized rotational speed f (NE) calculated by the above equation (1) is higher than the actual engine rotational speed NE when the internal combustion engine 10 is accelerated, and when the internal combustion engine 10 is decelerated. , Lower than the actual engine speed NE. That is, when accelerating or decelerating, the discretized rotational speed f (NE) corresponds to the engine rotational speed slightly ahead of the actual engine rotational speed (future). For this reason, in the present embodiment, the target throttle opening is calculated by pre-reading the engine speed during acceleration or deceleration, and therefore responds more quickly to a torque request for acceleration or deceleration. And acceleration and deceleration responsiveness can be improved.

  Further, the step width K may be always constant, but may be switched according to the acceleration or deceleration of the internal combustion engine 10. That is, when the acceleration or deceleration of the internal combustion engine 10 is large, the change in the actual engine speed NE is fast. Therefore, increasing the step width K can more reliably prevent the sudden operation of the throttle valve 20. It is possible and preferable. On the other hand, when the acceleration or deceleration of the internal combustion engine 10 is small (including the steady state), the deviation between the actual engine speed NE and the discretized speed f (NE) is smaller when the step width K is reduced. Therefore, it is preferable. Therefore, for example, two types of step widths of K1> K2> 0 are prepared, and when the acceleration or deceleration of the internal combustion engine 10 is equal to or greater than a predetermined value, the larger step width K1 is used for discrete operation. When the rotation speed f (NE) is calculated and the acceleration or deceleration is not more than the predetermined value (including the steady state), the smaller step width K1 is used to make the discretization speed f (NE) May be calculated.

  By the way, in the above equation (1), the discretization speed f (NE) at the time of steady state of the internal combustion engine 10 is the same as that at the time of acceleration, but the discretization speed f (NE) at the time of steady state is It may be the same. In the present invention, the discretization speed f (NE) may be the same regardless of whether the vehicle is accelerating or decelerating. Furthermore, in the above equation (1), when the internal combustion engine 10 is idling, the idling target speed is set to the discretized speed f (NE) regardless of the actual engine speed NE. K × (N−1) may be set as the discretized rotation speed f (NE).

  In the first embodiment described above, the ECU 50 adjusts a plurality of required torques to calculate the target torque, whereby the “target torque setting means” in the first invention is based on the block diagram shown in FIG. By calculating the target throttle opening, the "target throttle opening calculating means" in the first invention calculates the actual engine speed NE based on the signal of the crank angle sensor 42, thereby calculating the target throttle opening in the first invention. The “engine speed detection means” calculates the discretization speed f (NE) based on the above equation (1), thereby realizing the “discretization speed calculation means” in the first invention. Yes.

It is a figure for demonstrating the system configuration | structure of Embodiment 1 of this invention. It is a functional block diagram at the time of ECU calculating a target throttle opening. It is a figure which shows the relationship between real engine speed NE and discretization speed f (NE).

Explanation of symbols

10 internal combustion engine 12 piston 16 intake passage 18 exhaust passage 20 throttle valve 26 catalyst 32 intake valve 36 exhaust valve 50 ECU

Claims (4)

Target torque setting means for setting the target torque of the internal combustion engine;
A target throttle opening calculating means for calculating a target throttle opening for realizing the target torque according to the target torque and the engine speed, based on a characteristic model of the engine intake system;
Engine speed detecting means for detecting the actual engine speed;
Discretized rotational speed calculation means for calculating a discrete rotational speed obtained by discretizing the actual engine rotational speed with a predetermined step width;
With
The control apparatus for an internal combustion engine, wherein the discretized rotational speed is used as the engine rotational speed input to the target throttle opening calculating means. The actual engine speed is NE, the step width is K, and N is
K × (N-1) <NE <K × N
Is a natural number that satisfies
The discretized rotational speed calculation means calculates the discretized rotational speed as K × N when the internal combustion engine is accelerated, and calculates the discretized rotational speed as K × (N−1) when the internal combustion engine is decelerated. The control apparatus for an internal combustion engine according to claim 1. Acceleration / deceleration calculating means for calculating acceleration and / or deceleration of the internal combustion engine;
Step width changing means for changing the step width based on the acceleration and / or deceleration;
The control apparatus for an internal combustion engine according to claim 1 or 2, further comprising:   4. The internal combustion engine according to claim 3, wherein the step width changing means increases the step width when the acceleration and / or the deceleration is larger than a predetermined value as compared with a case where the acceleration and / or the deceleration is not larger than the predetermined value. Control device.

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